Composite brazing of C/C composite and Ni-based superalloy using (Ag-10Ti)+TiC filler material

Abstract

With the aim of alleviating the residual thermal stress in the C/C-GH3044 joints, a novel composite brazing, which combines Ag-Ti reactive composite brazing and TiC particle-reinforced composite brazing, was adopted for joining C/C composite to Ni-based superalloy GH3044 using (Ag-10Ti)+TiC composite filler material. The results showed that the composite interlayer was strengthened by four kinds of reinforcements, containing the introduced TiC, the in situ synthesized AgTi and Ti 2 Ni phases, and the residual Ti particles. With increasing TiC content from 0 to 32 %, the thermal expansion coefficient of the composite interlayer declined by 18.2 %, which is helpful in alleviating the residual thermal stress in the joints. In addition, the introduced TiC particles decreased the fluidity of the filler material and inhibited the inter-diffusion of atoms between GH3044 and filler material. As a result, the continuous brittle compound Ti 2 Ni in the composite interlayer was effectively reduced, so the composite interlayer had good plasticity. Meanwhile, the thickness of the composite interlayer gradually increased from 260 μm to 520 μm, and the finite element analysis showed that the corresponding peak value of von Mises stress decreasedby 20.1 %. The highest shear strength of the joints was 67.2 MPa obtained with (Ag-10Ti)+24 %TiC at 1020°C for 30 min,which is almost the same strength as the C/C composite matrix used in this study.